Conventionally, a formed cutter is used to form a complicated shape on an object to be cut. For instance, a stator blade used in a steam turbine, a gas turbine, a compressor or the like, has a complicated shape such as a shape of a Christmas tree at a root part thereof. Normally, the root part is formed into the complicated shape by cutting work by means of the formed cutter.
For instance, Patent Document 1 (JP2007-245277A) discloses a formed cutter for forming a complicated shape such as a Christmas-tree shape on an object to be cut by rotating a blade tapering toward the blade tip around its rotation axis. The blade of the formed cutter has depressions and projections that have different tool diameters. The depressions and the projections are alternately disposed along the direction of the rotation axis. The flutes are formed between adjacent pair of cutting parts to positively discharge grinding swarf. The flutes become larger in width toward the tip side of the tool.
The rake face of the blade of the formed cutter is normally formed by grinding by means of a disk grinder.
FIG. 7 is a perspective view showing the disk grinder grinding the rake face of the formed cutter. As shown in FIG. 7, the disk grinder 100 rotates in a direction of an arrow to grid the rake face 4 of the blade 2 which is disposed on the tip side of the formed cutter.
The formed cutter 1 with the rake faces 4 rotates around the rotation axis O in a feed motion to process a surface of an object (object to be cut) by means of a cutting part 6. The helical tooth shown in FIG. 7 is normally used as the cutting part 6 of the formed cutter 1. This is to distribute stress generated during the cutting process. The flutes are formed between the adjacent pair of the cutting parts 6. The flutes are commonly formed by the disk grinder 100 as well.
Although it is not a formed cutter, Patent Document 2 (JP2007-245337A) discloses a double-cone grinding wheel as a grinding wheel for grinding general cutting tools. The double-cone grinding wheel is formed as a peripheral ridge with roof sides converging toward it.